[daip] reading 1996 uv-fits data in 15OCT99 AIPS

[Eric Greisen]

Philip N Appleton writes:

 > I have some uv data written with FITTP onto tape (blocking factor 10)
 > in Mar 1996. I am trying to combine this data (which was taken with
 > the C-array) with more recent (1999) dat taken with the B
 > array. However, my current version of AIPS (15OCT99) does not seem to
 > recognize the records--presumably because there was was change of
 > format after 1996. Is there something in 15OCT99 which will allow me
 > to read the older formatted data? 

        The format has in fact not changed in a way to cause serious
problems.  If the data are partically calibrated, then there may be
problems with the formats of calibration files.  However, we have
written code in recent years to translate such changes on the fly.

Your problem is more basic.
 > 
 > The data is on tape in separate fits files-- for various reasons I
 > cannot mount my alphastation500 tape drive directly and so have to
 > read the tape into a disk file with dd. I am using 
 > 
 > dd if=/dev/drive of=uvdata_1 bs=18800           
 > 

   Why did you choose 18800?  You must use what is on the tape, which
will be n * 2880 bytes with the default n = 10.  Using 18800 reads the
first 18800 bytes of each tape record discarding the remaining 10000
bytes. 

 > then using uvlod from 15OCT99 which then produces the following
 > message
 > 
 > Task UVLOD  (release of 15OCT99) begins
 > cartwh> UVLOD1: ZTPOPD: using translated file name =
 > cartwh> UVLOD1: ZTPOPD: /local/phila/phil/a118_c_fin/FILE1
 > cartwh> UVLOD1: Found ARP118   observed on 17-MAR-1996
 > cartwh> UVLOD1: UV data will be written in compressed format
 > cartwh> UVLOD1: Create A118C_CH0   .ICON  .   1 (UV)  on disk  2  cno   13
 > cartwh> UVLOD1: UVFDAT: ERROR READING TAPE. IERR=     4

   This means premature end of file - a reasonable result when
10000/28800 of the data have been discarded.

 > cartwh> UVLOD1: Destroyed  1 extension files of type HI
 > cartwh> UVLOD1: Destroyed UV image file: catno=     13 disk= 2
 > cartwh> UVLOD1: Purports to die of UNNATURAL causes
 > cartwh> UVLOD1: cartwheel 15OCT99 TST: Cpu=     0.5  Real=     3  IO=       515


Eric Greisen